The present invention relates to a film perforator that can transport a film stably at a high speed.
In the conventional film perforator as shown in FIG. 3A, film 2 delivered from supply reel 1 is supported by being nipped between feed roller 3 and pad roller 3, and is supplied to punch unit 5 through guide chute 4. Film 2 is perforated by punching at punch unit 5, thereafter proceeds through sprocket 6 which comes into engagement with the perforations, side mark printer 7 and second sprocket 8 in order, and is then reeled up by take-up reel 9. As shown in FIG. 3B, when film 2 passes through punch unit 5, film 2 is transported at high speed between stripper 5c and die 5d while punches 5a and pilots 5b are moving upward. In this case, since the space l between stripper 5c and die 5d is quite narrow (about 1.0 mm to 1.3 mm), if film 2 is not exerted with sufficient tension so as to keep its proper flatness or stiffness, film may touch stripper 5c or die 5d while being conveyed, creating scratches or static electricity. In order to keep film 2 taut, in the above conventional apparatus, there is incorporated means 2' for providing film 2 with backward tension. Specifically, a predetermined tension is achieved by using a vacuum pump or a blower, or dancer roller, which is not shown in FIG. 3a.
However, the above means for tensioning to the film is complicated in structure and needs a large installation space. Additionally, there is a problem that it is difficult to convey the film stably at high speed.